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Easy20 min

CSRF Password Change

By @gorka

Red social donde el endpoint de cambio de contraseña acepta la nueva contraseña sin verificar la contraseña actual, haciendolo vulnerable a CSRF.

This hack was reported with no reward

1.2K views77 completedUpdated Nov 2026
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Hackers who solved it· 8

JM1
@overtone13 days ago
m275809282
@m2758092816 days ago
DA3
@david.pow.m18 days ago
moidlahoz02
@moidlahoz0222 days ago
lydiel
@lydiel23 days ago
ferrergonzalezantonio4
@ferrergonzalezantonio427 days ago
espejoramirezhugo
@espejoramirezhugo27 days ago
IS
@isaacrojas19841Oct 2026

Objectives

1
Identificar PUT /api/users/password
2
Notar que solo pide newPassword (no oldPassword)
3
Crear PoC CSRF que cambie la contraseña
4
Demostrar takeover de cuenta

Information

Difficulty
Easy
Duration
20 min
Bounty
Sin recompensa
Completed
77
Creator
gorka@gorka
Updated
Nov 2026

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Tools

Burp SuiteEditor HTML

Prerequisites

  • Conocimiento basico de CSRF
  • HTML/JavaScript

Tags

CSRF

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Despliegue

# Opcion 1: autodeploy
./autodeploy.sh

# Opcion 2: manual
docker compose up --build

# Acceder
https://localhost:1000

Compatible con macOS, Linux y Windows (Docker Desktop / WSL).

Para parar:

./autodeploy.sh destroy
# o: docker compose down -v

Contenido del Lab

La aplicacion

Chirp es una red social con gestion de cuenta y cambio de contraseña.

La vulnerabilidad

PUT /api/users/password cambia la contraseña aceptando solo newPassword sin verificar la contraseña actual ni token CSRF.

Cadena de ataque

1. Interceptar peticion de cambio de contraseña
2. Notar que no pide oldPassword
3. Crear PoC: fetch PUT con newPassword
4. Victima visita → Contraseña cambiada
5. Login con nueva contraseña → ATO

Solucion interactiva

Accede a /writeup dentro de la aplicacion para una guia paso a paso con botones interactivos.


Flag

(contraseña cambiada exitosamente)

Remediacion

  1. Requerir contraseña actual para cambios de contraseña
  2. Tokens anti-CSRF
  3. Rate limiting en cambio de contraseña

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